Lectins as defenses. Characterization of the major egg protein of the snail Pomacea diffusa

DREON, MARCOS S.; BROLA, T; HERAS, HORACIO

Córdoba

Congreso; 52th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2016

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular

Pomacea freshwater snails lay eggs above the water line, exposing them to high temperatures, desiccation and predators. Recent studies showed that Pomacea egg carotenoproteins, provide not only embryo nutrition, but also unexpected defenses against predation. In this work we isolated and characterized PdPV1, the most abundant egg protein of P. diffusa. The carotenoprotein was isolated from egg homogenates by ultracentrifugation and size exclusion chromatography (SEC). PdPV1 molecular weight and global shape were estimated by PAGE, SEC and small angle X-ray scattering (SAXS). Thermal stability was evaluated by fluorescence and absorption spectroscopy and SAXS. Carbohydrate content determined by colorimetry. PdPV1 resistance to gastrointestinal digestion was evaluated in vitro and its lectin activity by hemagglutination assays.PdPV1 is an anisometric oligomer of 422 KDa, composed by 5 subunits of 23, 25, 29, 30 and 33 KDa. The protein is highly glycosylated (8.90% w/w), thermostable (up to 65ºC) and resists 2h of simulated gastrointestinal digestion. PdPV1 was able to agglutinate rabbit erythrocytes.The presence of an egg carotenoprotein with lectin activity resistant to gastrointestinal digestion suggest a protective role against predation similar to that well established for defensive lectins of plants. In animals, lectins alike were only reported in a related snail.